While data can be transmitted on a single line in a serial fashion, it is much more efficient, rapid and useful to transfer data bits on parallel lines which constitute a bus. Thus, a bus which can provide parallel transfer of four or more bits simultaneously can be considered a wide bus.
Of course, the wider the bus the more data bits can be simultaneously transferred in parallel, thus saving many time units in the transfer of significant data.
Generally, the conventional parity check schemes which are used with wide data bus communications are accomplished by the single bit parity generation scheme, whereby a single bit of parity is generated at the driver-end of the bus and whereby the receiver-end of the bus is used to check the parity bit in order to establish the occurrence of a normal transmission or an error-incurred transmission.
In the single bit parity generation scheme, this system is relatively useful if each driver unit and each receiver unit are "single-bit oriented".
However, in modern circuitry applications, in order to reduce the cost of elements, it is general standard use that most of the driver chips and receiver chips are designed as "multiple" driver units and "multiple" receiver units into a single package.
The single bit parity generation-detection scheme has a certain liability in that it fails to detect many cases of common failures when an entire chip has failed. In these cases of whole chip failure, the situation occurs where all of the drivers and all of the receivers in the particular package are inoperative or have failed. As a result of this, the final result will show anywhere between no error occurring to showing the complete failure of all "k" bits, where "k" is a number of drivers or the number of receivers in the particular chip.
Additionally, the symbol "n" will represent the number of lines constituting the entire wide bus.